Material for tanning and process of making the same



Pasta Dec. 18,1928.

NEW YORK, ,ASSIGNORS T0 YORK.

- MATERIAL FOR TANNiNG AND No Drawing.

., material thus formed so that a soluble sulphonic acid compound is-formed. The term, phenolic body is used herein to refer to the monohydroxy aromatic compounds in which the hydroxyl group is attached directly to a ring carbon atom, and includes not" only phenol but .also related compounds having one or more than one closed chain or benzene radical.

It is desirable to have a material that will,

tan hid-es to a white or light color, in a shorter time and with a less expenditure of tanning material than that required with the commonly used tanning materials. When a vegetable tan is used, the tanning of the light weight leathers usually requires two to four days, while heavy leathers usually require four weeks or more. The tanning solutions must be discarded while they still contain approximately 12% of the original tanning material. rials are known which require less time than the vegetable materials, but these materials frequently make yellowish or brownish leathers and such leathers ofter have a horny or tinny feel and do not have the full body that is required in commercial leathers.

We have discovered a group of excellent tanning materials which complete this action in one-half to one-fourth the time required by vegetable materials. Solutions of these materials can be used until the tanning mate- .rial is practically completely consumed -be-- cause even the dilute solutions have the desired rapid action on skins.- The leathers tanned with these materials are light colored.

The lighter skins such as sheep and calf can betanned to awhite or nearly white color and they'havea gobd full body and a soft silky feel. A

Broadly our. process consists in using amounts of the phenolic'body' and aldehyde such that more than one phenolic radical is present and capable of condensing with an aldehyde radical carrying out the reaction in the presence of a condensing agent; and then sulphonating; the condensation product may becarriedout in the" presence of a small Various synthetic tanning mate-- I -1,695,655 UNITED STATES PATENT OFFICE.

creamer. J. nnnnmz AND nitrnun-nnnsnnu. mArnEson, or maeem 1a NIACET CHEMICALS CORP., A CORPORATION OF NEW rnocnss or MAKING THE smnl Application filed- March 7, 1928. 7 Serial No. 259,917..

amount of acid but larger amounts of acid.

and can be used in the process without seriously affecting the properties of the products. Phenol or cresols and paraldeyde or acetaldehyde in proportions such that two phenol radicals will combine with one aldehyde radical are preferred, but the other phenolic bodies and aldehydes of higher and lower molecular weight may be'usedin" equivalent proportions.

We have prepared a tanning'mat'erial bymelting 100parts of phenol to which has been added 0.25 parts of concentrated sulphuric acid and then slowly adding- 23.4 parts of paraldehyde. The mixture-Was stirred and maintained. at a temperature of 45 to 55 C. for about two hours or until the reaction was complete.

This product was then sulphonated by pouring it, into 100 parts of concentrated sulphuric acid. maintaining the temperature of the mixture between 45 and 55 C. The mixture was stirred at this temperature until the sulphonated product was soluble oruntil the sulphona-tion was complete and it .was'

' then diluted with water and the uncombined sulphuric acid neutralized. The sulphonated product is itself an acidic material. A product prepared as described is preferred for making most tanning baths on account of its degree of acidity and because the alkali sulphate is useful for plumpingthe leather, but solutions of less 'or greater acidity will tan hides satisfactorily and may b'e-prepared accordingly for special purposes. It is not necessary to complete the condensation before sulphonating. We have mixed phenol and paraldehyde in the proportions given in the above example and before the reaction was complete, poured the mixture with stirring'into the' above named excess of concentrated sulphuric acid at a rate such that the temperature was maintained at {15v to 55 C. When the condensation and sul- I phonation were complete the mixturewas diluted and the excess of sulphuric acid was neutralized. I p

The product is a water soluble material and usually forms clear slightly yellow solu-- tions.- ,The solution maybe used alone for making baths for tanning hides or it may be 7 liquid permittingefiicient temperature conzinc.

used in conjunction with other tanning mate-' rials. Most of the'lighter hides come-out white when tanned ina bath made solely of a.

solution of this material but some of the heavier hides are sli htly colored, depending upon the nature of t e hide.

A temperature of 40 to 65 C. should not be departed from in preparing the material uct obtained by mixing the phenolic bodyand aldehyde into the acid, the mixture is trol, and the sulphonated product makes light colored leathers, but when the acid is added to the condensed product the mixture becomes pasty, the sulphonation is diliicult to control due to local overheating, and the .sulphonated product makes dark colored leather. 7 n

The higher molecular weight phenolic bodies such as the cresols, xylenols and naphthols tend to make a material that colors the leather. When the product is made of such materials or when such materials-are present,

we carry out one or more of the steps of the process in the presence of a small amount of Other means for producing nascent hydrogen, such as the presence of an amalgam or electrolysis, will also diminish the coloring properties of the material. The reducing agent may be and is preferably used in making all of these tanning materials as there is a tendenc to form products that color the leather slig tl but it is sometimes not nec essary to use t e zinc, in order to make a satisfactory product when araldehyde and phenol are used and when 't e temperature is closely controlled. The zinc may be added during the condensation, during the sulphonation'or after the sulphonated compound is formed but we prefer to have the zinc present during the sulphonation. The addition of 1 to 4 parts of zinc per 100 parts of the phenolic body is usually suflicient to mt ke a light colored tanning material.

Weclaim as our invention:

1. The process of making a tannin material which comprises condensing a p enolic bodycontainmg one hydroxyl group and an aldehyde containing one or More carbon atoms at a temperature of 40 to .0. in'the rial which comprises condensing a p enolic,

presence of a small amount of a condensing agent, and adding the condensed material to an excess ofsul'phuric acid at said temperature to form a soluble roduct. 2., The process of ma 'ng a tannin matebody containing one hydroxyl group and an aldehyde containing one or more carbon 8. In the process of making a tanningmaatoms at a temperature of 40 to 65 C. in the presence of a small amount of a condensing agent and adding the condensed material to an excess of sulphuric acid at said temperan excess of sulphuric acid at said temperature to form a soluble product, one or more of the steps being carried out in the presence of a small amount of zinc.

4. The process of making a tanning material which comprises condensing a phenolic body containing one hydroxyl group and an aldehyde containing one or more carbon atoms at a temperature of 40 to 65 C. in the presence of a small amount of'a condensing agent and adding the condensed material to an excess ofsulphuric acid at said temperature to form a soluble product, the sulphonation being carried out in the presence of a small amount of zinc.

5. The process of making a tannin material which comprises condensing a p enolic body containing one hydroxyl group and an aldehyde containing one or more carbon atoms at a temperature of 40 to 65 C. in the presence of a small amount of a condensing agent, adding the condensed material to an excess of Sn] huric acid at said temperature to form a so uble product and then treating the sulphonated product with a small amount of zinc. p v v 4 6. The process of making a tannin material which comprises reacting'a phenolic body containing one hydroxyl group and an aldehyde containin one or more carbon atoms in the presence 0 a small amount of a condensing agent at a temperature of 40 to 65 C.,

the proportion of phenolic body to aldehyde 7. In theflprocess of making a tanning terial which comprises condensing anamount of a phenolic body containing one hydroxyl group and an aldehyde containinggone or more carbon atoms so that one aldehyde radical is'linkedwith more than one phenol rad: 1

ical and then 'sul honating the material, the step consisting o addin the condensed ma- '.terial to an excess of su huric. acid for 5111- phonating' the conden I compound whilst the reaction terial which comprises condensingan amount mixture is maintained at 40 to of a phenolic body'containing one hydroxyl group and an aldehyde containing one-or more carbon atoms so that one aldehyde -radical is'linked with two phenol radicals and then sulphonating the material, the step consisting of addin the condensed material to an excess of sulp uric acid for sulphonating the condensed compound whilst the reaction mixture is maintained at 40 to 65 C.

9. The sulphonated condensation product which forms an almost colorless solution in water and which tans skins and hides giving white or nearly white leather,'0bta1nable when a monohydroxy aromatic'hydrocarbon containin one or more benzene radicals is condense with an aldehyde containing one or more carbon atoms in the roportion of one aldehyde radical to two hy oxyl compound radicals and the condensation roduct is sulhonated, the condensing-an sulphonating eing carried out at 40 to C.

10. The sulphonated condensation product I which forms an almost colorless solution in water and which tans hides giving light colored leather, obtainable by treatm parts phenol and a small amount of sulp uric acid with 23.4 parts of araldehyde at a temperature of 40 to 65 to form a condensation product, pouring the condensation roduct into an excess of concentrated sulp uric acid while maintaining the reaction mixture at 40 to 65 C. and then neutralizing the excessof free acid.

11. The process of making a tanning material which comprises adding a phenolic body containing one hydroxyl group and an aldehyde containing one or. more carbon atoms. 

